Regarding the audio interface, it depends on your budget and the result you want to achieve. I should also tell you that the final result depends heavily on the piano and the environment in which you record. What I mean by this is that it's useless to buy a 2000 euro audio interface with fantastic preamps and divine converters if you then have to record an upright piano inside a 2m x 2m room. Clearly, good audio interfaces cost quite a bit of money. For ultra-professional results, instead of using an audio interface that also includes microphone preamplifiers, separate converters and preamps are normally used, which are chosen based on what you want to record. Quality in recording takes many variables into account. To make a record, you start from the choice of instrument, move to the choice of the room, which must have a certain acoustics, up to the audio capture chain: microphones, preamplifiers, and converters. I don't know anything right now, so it is difficult to give you advice. It would be necessary to know what budget you have, what piano you have, and where you intend to record.
If you don't have high demands, you could opt for one configuration; however, if you do have high demands because you have been provided with an excellent concert grand piano in a beautiful hall, then you must opt for other configurations.
Ribbon microphones are not used for piano recording. I have never witnessed a piano recording with ribbon microphones; let's just say they are not very suitable. They have a very dark sound and are normally used with instruments like the guitar. In some mixing contexts, the ribbon microphone sounds very good, but it is certainly not the case for a solo instrument like the piano. Moreover, you have to be very careful with ribbon microphones because if you forget to deactivate the Phantom power, they will burn out.
The ribbon microphone is made of a thin metal foil—we're talking about microns in thickness—therefore an external power supply would overheat this foil, causing it to burn immediately. In short, they are very delicate microphones and honestly, I have only seen them used on very rare occasions.
For piano recording, one opts for a pair of condenser microphones, preferably small diaphragm, but you can also record with large diaphragm microphones. It always depends on the sound you want to achieve, and thus in this case too, there would be a need to know the repertoire you want to record. The same applies to positioning: close positioning for pop and jazz recordings, more distant positioning for classical recordings. The same goes for the pickup technique. ORTF, AB... Everything depends on the sound you want to obtain. But we keep coming back to the same point: if we are recording a studio grand piano, one cannot expect it to sound like a concert Steinway in the recording. Instruments also have their limits. Finally, as I was telling you about the room: in a home living room, we cannot expect to have the same acoustics as a concert hall. Aside from the amount of reverb, which is the least of it, in a small room there are a million sound reflections, creating comb filters. There are so many physical variables that complicate the recording procedure.
Everything is aimed at the result you want to achieve. If you can be a little more precise, I will try to be more precise as well. See you soon.
